Machine for pulverizing or grinding coal and other materials



5 Sheets-Sheet 1 Julyl e, i926.

P. W. GRIFFIN MACHINE FOR PULVERIZI'NG 0R GRINDING COAL AND OTHER MATERIALS Filed July 20, 1923 July 6,1926., v3,591,758

P. W. GRIFFIN MACHINE FOR PULVERIZING OR GRINDING COAL AND OTHER MATERIALS Filed July 2o, 1923 s sheets-sheet 2 July 6 w26.

P. W. GRIFFIN MACHINE FOR PULVERIZING OR GRINDING `COAL AND OTHER MATERIALS Filed July 20, 1923 5 Sheets-Sheet 3 Patented July 6, 1926.

UNITED STATES PATENT OFFICE.

P ERCY WALTER GRIFFIN, F ENFIELD, ENGLAND, ASSIGNOR OF ONE-HALF T0 'VICKERS LIMITED, 0F WESTMIN STER, LONDON, ENGLAND, A REGISTERED BRITISH COMPANY. Y

MACHINE FOR PULVERIZING 0R GRINDING COAL AND OTHER MATERIALS.

Application led July 20, 1923, Serial No.

The invention provides the hereinafter V described and claimed improved machine of the horizontal type for pulverizing or grinding coal and other materials. By horizontal type is meant a kind built about a horizontal shaft and employing a grinding rotor comprising a fixed inding annulus, and a wheel revolvin within the annulus and carrying aroun in pockets of its periphery balls or rollers adapted to work against the vbore of the annulus by centrifugal action, the material to be treated being fed by suction into the centre of they wheel and centrifugally thrown into the grinding annulus. The invention has the prlmary distinctive features that the grinding wheel, revolving abouta horizontal shaft, is constructed to operate as a suction fan for the purpose of lcreating suction upon an opening at its side to draw the material to be treated into said wheel by said suction, and to subsequently centrifugally throw it into the grinding annulus or ring. Thefpresent invention also combines in one machine, upon the same axial shaft, a grinding rotor aforesaid and a beater rotor`,"'each working in a separate chamber of a casing, but communicating by an opening, between the two chambers, which opening forms the exit for the material from the chamber of the beater rotor and the entrance of said material into the chamber of the grindingl rotor, the grinding wheel 'having its fan-like action on said opening to create a suction. To this opening is applied l.a renewable screen determinin the size of the material allowed to pass. n the closed side ofthe grindin wheel a chamber is provided into which tie ground material from the grinding rotor is discharged. Through this chamber a suction is created b a fan from-an adjustable air inlet of sai chamber, through a separatingbox of large capacity, to an outlet. v

As the amount of air drawn through this chamber can be regulated from the air inlet, different gradings of ground material can be lifted with the air into the separating box,

652,803, and in Great yBritain July 25, 1922.`

-beater rotor creates air currents tending to treated, so that said dry the material being di e grin ng rotor 1n a material passes into t dry condition.

The drawings show a convenient and desirable adaptation ofthe invention.

Fig. 1 is a vertical section.

Fig. 2 isa transverse section through the beater chamber.

Fig. 3 is a right-hand end elevation of Fig. l.

Fig. 4 is a-transverse grinding chamber.

Figs. 5 and 6 show a modified form of a grinding rotor and annulus in which rollers are used instead of balls.

Within a stationary enclosing casing a are provided two rotors c andd revoluble with a common horizontally arranged shaft e, having bearings at f and g outside sai casing. The latter is divided into two chambers 02,'2 and the rotor c, which is a beater one, revolves within the chamber c2, and the rotor d, which has a grinding or finishing operation, revolves within the chamber d2. The two chambers are separate except for the large central opening h, to which is tted a id-like screen h2 through which the material must pass from the beater chamber into the grindinv` chamber.

The beater chamber is `lined with hard wearing renewable serrated linings es, and the upper part of it is furnished with a circumferential series of metal bars c* to form an impact surface.

The beater rotor is formed by a number of radial arms c5 projecting from a hub c and reversely -bent at right-anglesat their outer ends c7. Instead of right-angled ends said arms may be furnished with impact section through the or impact one and operates within the chamber to break down material to a size sufficient for it to pass through the grid h2, the action of this rotor also displacing air to have a drying eli'ect upon the material.

Material to be treated enters the beater chamber at 2, falling from the hopper i, or being suitably conveyed therefrom into said chamber, as, for example, by a screw conveyor driven by the wheel 3.

The grinding or finishing chamber d2 is furnished with a fixed annulus, j, of durable material and preferably made in halves as shown. The bore of this annulus is grooved at 7'2 for balls 7c to Work in, or said bore may be fiat, as shown in Figs. 5 and 6, for flat rollers c to contact. i

The grinding rotor al is in the form of a wheel revolving Within the annulus and hav-A ing a series of spaced pockets or recesses, d3, on its periphery in each of which is a ball c free to revolve. As the grinding rotor revolves the balls are carried round in contact with the groove of the annulus by centrifugal force. The driving end of each pocket is fitted with an easily renewable stud m against which the ball abut-s.

The bottom of each pocket is radially slotted at d4 to communicate with the hollow interior of the Wheel, which interior communicates with the opening h of the beater chamber o2. The back side of this wheel is closed as shown at d5.

The hollow centre of said wheel is formed by spaces d6 and intervening blades actinfr as spoke-like arms dl, extending from a hu d so that the construction of this centre creates air currents by operating 'fan-like, and centrifugally acts upon the material entering the chamber to throw same in a stream into the groove of the annulus in front of the grinding balls c.

The material to be ground is automatically drawn or sucked through the screen h2 into the hollow centre of the wheel through which it cannot pass axially, but is thrown radially through the slots d4, through the pockets d3, and into the groove of the annulus to be ground between the balls and the surface of said annulus, ultimately leaving said annulus by the space js.

A feature in the operation of this grinding Wheel or rotor is that its fan-like construction induces air currents through -the grid h2 from the beater chamber, and therefore sucks the material broken down through said grid into its own centre, to be centrifugally whirled into the grinding annulus and in a stream entering the annulus in front of the grinding balls or rollers.

The grinding chamber d2 on the back and closed side of the grinding Wheel is put into communication with a suction fan a2 by which the ground material is drawn out of the machine suspended in the air.

Between said fan and the back side of the chamber aforesaid is a separating box y and a passage s. The box admits of expansion of the oust-laden air. Air is admitted low down in the grinding chamber through an adjustable opening t controlled'by a hitand-miss regulating shutter t2. The upper end of the passage s can also be either fully open or partially closed by the hinged shutter u operated from the handle u2.

The control of the air inlet t, and the control of the passage s by the shutter u, com bined with the operation of the suction fan enables the grading of the ground material to be adjusted in relation-to the constant operation of the fan whereas the expansion of the dust-laden air in the separating box, y, insures material insutiiciently ground, or pulverized, to fall down the separating box and through the opening v into the grinding chamber again for regrinding by the grinding wheel.

w is a baiie provided within the separating box to give a circuitous fiow ot the dustladen air through the box and assist the separation of the heavier particles for regrinding.

The shaft.- e is driven by the belt e2 over the pulley e3, and the spindle of the suction fan :E by the belt 0 travelling over the pulleys o2, 03.

It will be clear from the foregoing that the fan-like construction of the grinding Vwheel exerts a suction on the opening L to which the grid h2 is applied, so that as soon as the material in the beater chamber is sufticiently small it is sucked through thc grid into the grinding Wheel, and whirled ccntrifugally into the grinding annulus in front of the balls lo.

It is to be understood that the walls of the beater chamber may be in any way conveniently provided for co-operation with the beaters to break up the material to the size suitable for passing axially through the grid into the grinding wheel.

It will be clear that the balls 7c are free to revolve Within the grooved bore of the annulus and Within the pockets or recesses, and that by centrifugal action they are kept in working Contact with the grooved bore of the annulus.

Apart from the current of air produced by the fan w, which air serves as the carrying medium for ground material, a current of air is continually passing through the machine by virtue of the operation ot the beater rotor, and more particularly by the fan-like grinding Wheel, this air keeping the machine cool and driving oli any moisture contained in the material.

Having now described my invention what I claim and desire to secure by Letters Patent is 1. A machine for pulverizing or grinding coal and'other material, comprising a stationary casing forming a grinding chamber the grinding chamber at an intermediate having an entrance opening at one side, a driven shaft passing horizontally through said chamber and opening, a grinding annulus fixed within said chamber coaxially of said shaft, a grinding wheel upon said shaft revoluble within said annulus and having openings therein at the side adjacent to the entrance opening of the grinding chamber, and grinding elements carried by said wheel and coacting with the inner face of said annulus, said wheel being also formed with blades adjacent to said central opening to provide a fan for drawing material into the grinding wheel through the said entrance 'opening solely by suction. i

2. A machine for pulverizing or grinding coal and other material comprising a stationary casing forming a grinding chamber having an entrance opening at one side, a driving shaft passing-horizontally through said chamberand opening, a grinding ann ulus fixed within said chamber coaxially of the shaft, a grinding wheel upon said shaft revoluble within the annulus and having blades disposed to operate as a suction fan with relation to said entrance opening to draw the material into the grinding wheel through the said entrance opening solely by suction, and grinding elements carried by the peripheral portion of said wheel and coacting with the inner face of the annulus. 3. A machine for grinding or pulverizing coal or other material, comprising a stationary casing forming a chamber, having an entrance opening at one side, a driving shaft passing horizontally through said chamber and opening, a grinding annulus fixed within said chamber co-axially of said shaft, a grinding wheel on said shaft revoluble within said annulus, grinding elements carried peripherally of said wheel, the latter being formed with blades constituting a suction fan for drawin material into said grinding wheel throug I said entrance opening, a separating box communicating with said chamber on the side of said grinding wheel opposite said entrance opening, said casing being formed with a passageway leading from the discharge side of said chamber to the side adjacent said entrance opening for returning insufiiciently ground material to the grinding wheel.

4. A machine for pulverizing or grinding coal or other material, comprising a stationary casing having a partition separating the space Within said casing into grinding and beater chambers, said partition having a screened `entrance opening to establish communication between the two chambers, a drivin shaft passing horizontally through the said chambers and opening, a beater mounted upon said shaft within the beater chamber, a grindin'o` annulus fixed within portion thereof and coaxially of said shaft,

a grinding wheel on the shaft freely revoluble within the annulus and having blades to constitute the sameras a suction fan which ary casing having a partition, separating the I space within said casing into grinding and beater chambers, said partition having an entrance opening placing said beater chamber and grinding chamber into communication, a driving shaft passing horizontally through said chambers and opening, a beater mounted upon said shaft within the beater chamber, a grinding annulus fixed within the grinding chamber at an intermediate portion thereof, and co-axially of said shaft, a grinding wheel on said shaft revoluble within the annulus, grinding elements carried peripherally of said grinding wheel and oooperable with the inner face of said annulus, said grinding wheel being formed with blades constituting a suction fan for drawing material from said beater chamber through said entrance opening into said grinding wheel, that part of said grinding chamber to the rear of said grinding wheel having a discharge passage for material and an adjustable yair inlet, and a separating box associated with said casing communicating with said discharge passage having an outlet for the discharge of ground material and suction means associated with said outlet.

6. In a machine for grinding coal and other material, a grinding chamber having an opening in'one side thereof, a grinding annulus within said chamber, a grinding wheel cooperating with said annulus provided with vanes formed on the side thereof adjacent to said opening and also with pockets between the said vanes and passageways leading from the pockets .to the peripher of the grinding wheel, the grinding W eel through the operation of the varies setting up a suction relatively to the opening of the grinding chamber to constitute the said grinding wheel as a self-feeding device, and grinding means between the annulus and the rinding wheel and exposed to the pockets Ey means of said passageways.

7. In a machine forgrinding coal and other material, a grinding chamber having an opening at one side thereof, a grinding annulus within said chamber, a grinding wheel mounted within said annulus and having vanes formed on the side thereof adjacent to the opening of the grinding chamber with pockets between the said vanes and passageways leading from the pockets td the periphery of the grinding wheel, the oppoand passageways, and balls loosely mounted site side of the grinding Wheel being closed, in the annulus and engaging the peripher the Yanes of the grinding wheel constituting of the grinding wheel and exposed through 10 suction-creating means by which the matethe passageways to the said pockets.

rial to be ground is drawn into the grind- In testimony whereof I have hereunto set ing wheel and passes out through the pemy hand.

riphery of the latter by way of the pockets PERCY WALTER GRIFFIN. 

